1. Field of the Invention
The present invention relates to an LED package, and more particularly, to an LED package having a lead frame structure with improved heat radiation performance, improved light reflection performance, improved electrical performance, improved moisture-proof performance and the like.
2. Discussion of the Background
An LED (Light Emitting Diode) is a device in which electrons and holes are recombined at a P-N junction to emit light when a current is applied thereto. Such an LED is generally fabricated into a package structure having an LED chip mounted thereto, and is frequently called an “LED package.” The LED package is configured to perform a light-emitting operation using a current applied thereto from the outside.
The LED package includes a lead frame for applying a current to an LED chip, and a housing for supporting the lead frame. In addition, the LED package may further comprise a light-transmissive encapsulant formed in a cavity of the housing to protect the LED chip from the external environment.
In an LED package, heat generated from an LED chip has a bad influence on the light emitting performance and life span of the LED package. This is because dislocation and mismatch occur in the crystalline structure of the LED chip in a case where the heat generated from the LED chip remains in the LED chip for a long period of time. Therefore, an LED package has been developed having a heat radiation means such as a heat sink additionally mounted at a position to which an LED chip is attached. However, the aforementioned LED package has a problem in that the structure thereof is complicated and the manufacturing costs thereof are increased since an additional component such as a heat sink should be installed.
Conventionally, an LED package structure has been developed, in which an LED chip is directly attached to one region of a lead frame and at least three terminal portions are branched off from the region of the lead frame to which the LED chip is attached. Such an LED package has been disclosed in Japanese Patent Laid-open Publication No. 2001-518692. However, in the disclosed conventional technology, a chip attaching region of a lead frame is reduced due to the structure in which three or more terminal portions are branched off from the chip attaching region. The reduction of the chip attaching region results in reducing an area of a region for reflecting light advancing backward from an LED chip, and thus, in degrading light reflection performance of the lead frame. Further, there is another problem in that the adaptability for an LED package having a plurality of LED chips mounted therein is reduced.
Meanwhile, in an LED package, a path through which moisture is penetrated around an LED chip in a housing from the outside of the housing along boundary surfaces between a lead frame and the housing and between the housing and an encapsulant is inevitably produced. Therefore, the penetration of moisture mainly causes the degradation in performance and life span of the LED package. Moreover, the lead frame is required to be bent near an outer surface of the housing. When bending the lead frame, therefore, the housing may be damaged or a gap between the lead frame and the housing may be further increased. The damage of the housing and the increase of the gap may cause moisture to more easily penetrate into the interior of the housing. Further, when bending the lead frame, a wire connected between a portion of the lead frame and the LED chip may be broken.